Your Test: Blood Cell Count
of cell, your doctor can tell how well your
immune system is working. This can help
identify infection, a reaction to certain medicines
or chemicals, or an illness such as leukemia.
Red blood cell (RBC) count
Red blood cells carry oxygen from the lungs to
the rest of the body. They also carry carbon
dioxide back to the lungs so you can breathe it
out. If your RBC count is low (which is called
anemia), your body may not be getting the
oxygen it needs. If the count is too high (a
condition called polycythemia), there is a risk
that your red blood cells will clump together
and block tiny blood vessels.
Blood is made up of red blood cells, white blood
cells, platelets, and plasma, which is the fluid
that carries blood cells.
A blood cell count finds the type and
numbers of cells in your blood. A
blood count can give your doctor
important information about your
health.
White blood cell (WBC) count
If you have an infection, white blood cells attack
and destroy the bacteria or virus causing it.
White blood cells are bigger than red blood cells,
and you normally have fewer of them. When
you have an infection, the number of white cells
can increase. Your doctor may use the number
of white blood cells you have to help identify
an infection or see how your body reacts to
cancer treatment.
There are several types of white blood cells.
Each plays a different role in protecting the
body. By looking at the numbers of each type
Two other RBC tests, hematocrit and
hemoglobin, can also help show if you have
anemia or polycythemia.
Hematocrit (HCT, packed cell
volume, PCV)
This test measures the amount of space (volume)
that red blood cells take up in your blood. The
value is given as a percentage. For example, a
hematocrit of 38 means that 38% of your blood's
volume is made up of red blood cells. The rest
is mostly plasma.
Hemoglobin (Hgb)
Red blood cells are mostly made of hemoglobin.
It carries oxygen and gives your blood its red
color. The hemoglobin test measures the amount
of hemoglobin in your blood. It can show how
well your blood can carry oxygen throughout
your body.
Platelet (thrombocyte) count
Platelets (thrombocytes) are the smallest type
of blood cell. They help your blood clot. When
you bleed, your platelets swell, clump together,
and form a sticky plug that helps stop the
bleeding. If there are too few platelets, you may
have trouble stopping the bleeding. If you have
too many platelets, you may have an increased
risk of forming a blood clot.
Blood smear
In this test, a drop of blood is spread (smeared)
on a slide and stained with a special dye. The
slide is then examined under a microscope. The
test shows the number, size, and shape of red
blood cells, white blood cells, and platelets.
Blood cells with unusual shapes or sizes can
help diagnose many blood diseases, such as
leukemia, malaria, or sickle cell anemia.
Do you have any questions or concerns after
reading this information? It's a good idea to
write them down and take them to your next
doctor visit.
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of this information, which does not replace medical advice. 2014-09-zx1261